Camshaft

ABSTRACT

A camshaft of an internal combustion engine may include at least one function device connected therewith via a shaft-hub connection. The function device may include at least two different function elements each operable for different function

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application DE 10 2012223 811.5 filed Dec. 19, 2012, which is hereby incorporated by referencein its entirety.

TECHNICAL FIELD

The present invention relates to a camshaft of an internal combustionengine having at least one function device connected therewith via ashaft-hub connection according to the preamble of claim 1. The inventionadditionally relates to a function device for such a camshaft and to aninternal combustion engine having at least one such camshaft.

BACKGROUND

Generic camshafts are thoroughly known, just as connecting functionelements to such camshafts, for example via a thermal joining fit.However, function devices such as for example gear wheels, drive wheels,cams, pump actuating devices, such as for example pump cams for ahigh-pressure pump or an Oldham coupling for the rotary connection ofvacuum or oil pumps are connected to the camshaft by way of pressed-inor thermally joined plugs up to now. For each function to be fulfilled,a separate function element, such as for example gear wheels or cams arerequired here, which for this purpose still have to be joined in adifferent way if need be. When joining camshafts in a cover module, anadditional aggravating fact is that the space is limited, so that it iseven more complex to keep a plurality of function elements to join aplug from the outside.

SUMMARY

The present invention therefore deals with the problem of stating animproved embodiment for a camshaft of the generic type, which ischaracterized in particular by a simplified production.

According to the invention, this problem is solved through the subjectsof the independent claims. Advantageous embodiments are subject of thedependent claims.

The present invention is based on the general idea of equipping afunction device on a camshaft with at least two different functionelements, which can each fulfil different functions. The functionelements combined in the function device in this case are connected tothe camshaft via a shaft-hub connection, for example via a thermaljoining fit or a longitudinal press fit. The principle idea thusconsists in combining or integrating as many function elements aspossible—however, at least two—in a common function device and merelyhaving to join this common assembly, i.e. the function device, to thecamshaft or a camshaft tube. This offers substantial advantages, forexample in the region of the weight, since a function device which isput together of a plurality of function elements is significantlylighter in construction weight than function elements that are eachseparately assembled. The function device according to the inventionadditionally makes possible a higher torque transmission than can berealised with a plug having a smaller internal diameter. At the sametime, the assembly is substantially simplified since all functionelements no longer have to be separately, i.e. individually, joined tothe camshaft, but merely the function device, in which the individualfunction elements are already aligned correctly to one another withrespect to an angle of rotation. This is a major advantage in particularif a camshaft is assembled within a cylinder head cover, since accordingto common knowledge only very little working space is available there. Afurther advantage can be seen in an optimised weight distribution, forexample through masses which are opposed to a drive belt pulley, so thatthe function device can be utilised for offsetting unbalances at thesame time.

Practically, at least one function element is a gear wheel, inparticular a coupling gear wheel, a cam, a pump actuating device, forexample in the manner of a cam, an encoder wheel, a belt pulley, acoupling, in particular an Oldham coupling, or a chain wheel. Even thisnon-conclusive listing gives an idea as to how flexible the respectivefunction device can be configured through the joining of individualfunction elements.

According to a further advantageous embodiment and solution according tothe invention, the function device is formed in one piece, in particularas a one-piece sintered component. In this case, the individual functionelements of the function device are thus connected to one another as onepiece, so that the function device can be completely formed in onepiece. This makes possible in particular a rational production of thefunction device, since an aligned joining together of the individualfunction elements into the function device can be omitted. Alternativelyto this, it can obviously also be provided that the individual functionelements of the function device are connected to one another in a fixedmanner, in particular welded, soldered, screwed or glued together. Theseparate formation of the individual function elements in turn offersthe major advantage that the function device is extremely flexiblyassemblable with respect to the individual function elements. Theindividual function elements in this case can be connected into thecontinuous function device via a friction welding connection or by meansof laser welding. In order to be able to facilitate joining theindividual function elements into the common function device in anangularly correct manner, positioning aids can be additionally providedon the individual function elements, which allow fixing of theindividual function elements on one another exclusively in a predefinedangular position. Such positioning aids can for example be formed as asingle flat, for example as a clear grind, or as a multiple flat, inparticular as a dual flat or triple flat. In this case, a functionelement thus has such a single or multiple flat as well as an associatedcomplementary recess arranged on the opposite face end, as a result ofwhich an angularly aligned axial inserting into one another of theindividual function elements into the common function device is veryeasily possible. Obviously, the positioning aids can be alternativelyformed also as a pin or associated opening, which allows a joiningtogether of two function elements in merely one single or a plurality ofpredefined angular positions. These positioning aids can obviously beadditionally utilised also for further adjusting and positioningoperations after the assembly of the camshaft, for example wheninstalling the camshaft in the cylinder head.

If one of the function elements is designed as an Oldham coupling, apump can for example be coupled to the cylinder head to the outside viathis. Such an Oldham coupling makes possible a coupling, in which thetorque is transmitted between two parallel shafts. Usually it consistsof three discs, wherein the outer two are fastened on the respectiveshafts or on the pump and on the function element and the middle one ismounted with respect to the two other discs in two slot and keyconnections which are positioned orthogonally to one another. Such anOldham coupling makes possible in particular compensating for minorparallel offsets between the camshaft and an axis of the pump, as aresult of which at least minor production inaccuracies can be offsetwithout problems, so that the entire construction altogether allowsgreater production tolerances.

Further important features and advantages of the invention are obtainedfrom the subclaims, from the drawings and from the associated Figuredescription with the help of the drawings.

It is to be understood that the features mentioned above and still to beexplained in the following cannot only be used in the respectivecombination stated but also in other combinations or by themselves,without leaving the scope of the present invention.

Preferred exemplary embodiments of the invention are shown in thedrawings and are explained in more detail in the following description,wherein same reference characters relate to same or similar offunctionally same components.

BRIEF DESCRIPTION OF THE DRAWINGS

Here it shows, in each case schematically

FIG. 1 a sectional representation through a camshaft with a functiondevice according to the invention in an internal combustion engine,

FIG. 2 a partially sectioned view of an internal combustion engineaccording to the invention in the region of two camshafts with thefunction device according to the invention,

FIG. 3 a representation as in FIG. 2, however with bearing bridges,

FIG. 4 different views of an a sectional representation through anembodiment of a function device according to the invention,

FIG. 5-7 function devices in each case with different function elements.

DETAILED DESCRIPTION

According to the FIGS. 1-3, a camshaft 1 of an internal combustionengine 2 according to the invention comprises at least one functiondevice 3 that is connected to the camshaft 1 via a shaft-hub connection,in particular via a press fit connection, which is put together of atleast two different function elements 4. The individual functionelements 4 in this case fulfil different functions and are merelycombined in the common function device 3 to simplify the assembly. Atleast one function element 4 in this case can for example be formed as agear wheel 5, in particular as a coupling gear wheel, as a cam, as apump actuating device, as an encoder wheel 6, as a belt pulley, as acoupling 7, in particular as an Oldham coupling, or as a chain wheel 5′.The function device 3 represented according to FIG. 1 thus has threefunction elements 4, namely the coupling 7, the chain wheel 5′ or gearwheel 5 as well as the encoder wheel 6. By combining a plurality offunction elements 4 in a common function device 3 the production of thecamshaft 1 is clearly simplified, since all function elements 4 nolonger have to be separately joined to the camshaft 1 but merely acommon function device 3, as a result of which the joining process canbe significantly rationalised. The function device 3 with a plurality offunction elements 4 is additionally lighter in weight than therespective separate function elements 4, as a result of which a weightsaving can be achieved, which in turn has a positive effect on the fuelconsumption.

Compared with a plug, the function device 3 according to the inventionadditionally makes possible a higher torque transmission, since via thetransverse press fit, for example produced by means of thermal joining,or a longitudinal press fit, a larger force-transmitting contact areacan be created. The combined arrangement of a plurality of functionelements 4 in a common function device 3 additionally offers majoradvantages in particular in the assembly of the function device 3 in acover or a cylinder head 8, since extremely confined space conditionsare usually encountered there.

According to FIG. 2, a view is shown from the top of the cylinder head 8of the internal combustion engine 2 with two camshafts 1, wherein on thelower camshaft 1 the function device 3 according to the invention isarranged. The latter, in turn, combines three function elements 4,namely the coupling 7, a gear wheel 5, in the manner of a coupling gearwheel for coupling to the second camshaft 1, as well as the encoderwheel 6. Mounting the camshafts 1 on the cylinder head 8 in this case iseffected by means of a bearing frame 9, which is connected to thecylinder head 8, i.e. an engine block, via screws 10. By way of thecoupling 7, which in particular can be formed in the manner of an Oldhamcoupling, a pump 11 for example can be coupled to the camshaft 1 in arotation-transmitting manner. The Oldham coupling in this case makespossible an at least minor parallelism of the axes of the camshafts 1and the axis of the pump, as a result of which the production precisionneed not be as high as without such an Oldham coupling.

Considering FIG. 1 it is evident that the function device 3 is formed inone piece, in particular as a one-piece sintered component, so that aseparate and prior assembly of the individual function elements 4 intothe common function device 3 can be omitted. Obviously, the individualfunction elements 4 of the function device 3 can also be alternativelyproduced separately and subsequently connected to one another into thecommon function device 3 in a fixed manner, in particular welded,soldered, screwed or glued together. In the representations according toFIG. 4 a function device 3 is shown for example, which integrates twofunction elements 4, namely the gear wheel 5 and the coupling 7 in onepiece. On the face end of the function device 3 facing away from thecoupling 7, a further function element 4, for example an encoder wheel6, could now be additionally attached or welded on.

In order to facilitate an assembly of a multi-part function device 3,positioning aids 12 can be provided on the individual function elements4, which allow fixing of the individual function elements 4 to oneanother exclusively in a predefined angular position. According to thelowermost representation in FIG. 4 and the FIG. 6, the positioning aid12 in this case is formed as a two-flat, wherein for example the encoderwheel 6 has a recess that is complementary thereto, in order to makethus possible an angularly orientated fixing. In general, thepositioning aid 12 in this case can also be formed as a single flat oras a multiple flat, in particular also as a triple flat. Generally, allother non-round shapes are obviously also conceivable for the accurateangular fixing of the individual function elements 4 on one another.

With the function device 3 according to the invention, a plurality offunctions in the form of different function elements 4 can thus becombined and in the manner of a common function device 3, fixed on thecamshaft 1 in a single operation. Because of this, not only the assemblyoperation can be significantly rationalised, but a cost-effectiveproduction achieved at the same time. By combining individual functionelements 4 into the common function device 3, the major advantage isadditionally obtained that compared with a plug, higher torques can betransmitted and in particular an assembly of the function device 3 ispossible even with comparatively little working space. Above all, thisoffers the possibility of keeping the function device 3 according to theinvention with the individual function elements 4 in a cover andsubsequently slide the camshaft tube through the function elements 4 andthe individual bearing points for example of the bearing frame 9.Through the integration of a plurality of function elements 4 in acommon function device 3, merely the fixing of a function device 3 isrequired in this case, which is clearly simpler than the previouslyrequired fixing of the individual function elements 4. With the functiondevice 3 according to the invention, a weight saving can be additionallyachieved, since the individual function elements 4 can be formed in aweight-reduced manner. An unbalance offset in particular for examplewith respect to a belt pulley 13 (see FIGS. 2 and 3) can also beachieved through a special arrangement of the individual functionelements 4.

1. A camshaft of an internal combustion engine, comprising: at least onefunction device connected therewith via a shaft-hub connection, whereinthe function device includes at least two different function elementseach operable for different functions.
 2. The camshaft according toclaim 1, wherein the function device couples to the camshaft via atleast one of a thermal joining fit and a longitudinal press fit.
 3. Thecamshaft according to claim 1, wherein at least one function element isat least one of a gear wheel, a coupling gear wheel, a cam, a pumpactuating device, an encoder wheel, a belt pulley, a coupling, an Oldhamcoupling, and a chain wheel.
 4. The camshaft according to claim 1,wherein the function device is formed in one piece as a one-piecesintered component.
 5. The camshaft according to claim 1, wherein theindividual function elements of the function device are fixedlyconnected to one another via at least one of welding, soldering,screwing and gluing together.
 6. The camshaft according to claim 5,wherein the individual function elements of the function device comprisepositioning aids, wherein the positioning aids allow fixing of theindividual function elements to one another in a predefined angularposition.
 7. The camshaft according to claim 6, wherein the positioningaids are at least one of formed as single flat and as multiple flat, inparticular as one of a two-flat and a triple-flat.
 8. A function deviceof a camshaft, comprising: at least two different function elementsfulfilling different functions, wherein the function device is at leastone of formed in one piece as a one-piece sintered component and theindividual function elements of the function device are connected to oneanother in a fixed manner via at least one of welded, soldered, screwedand glued together.
 9. The function device according to claim 8, whereinat least one function element includes at least one of a gear wheel, acoupling gear wheel, a cam, a pump actuating device, an encoder wheel, abelt pulley, a coupling, an Oldham coupling, and a chain wheel. 10.(canceled)
 11. The camshaft according to claim 2, wherein at least onefunction elements is at least one of a gear wheel, a coupling gearwheel, a cam, a pump actuating device, an encoder wheel, a belt pulley,a coupling, an Oldham coupling, and a chain wheel.
 12. The camshaftaccording to claim 3, wherein the individual function elements of thefunction device are fixedly connected to one another via at least one ofwelding, soldering, fastening, screwing, and gluing together.
 13. Thecamshaft according to claim 12, wherein the individual function elementsof the function device comprise positioning aids, wherein thepositioning aids allow fixing of the individual function elements to oneanother in a predefined angular position.
 14. The camshaft according toclaim 13, wherein the positioning aids are at least one of formed assingle flat and as multiple flat.
 15. The camshaft according to claim14, wherein the multiple flat is at least one of two-flat and tripleflat.
 16. The function device according to claim 8, wherein theindividual function elements of the function device comprise positioningaids, wherein the positioning aids allow fixing of the individualfunction elements to one another in a predefined angular position. 17.The function device according to claim 16, wherein the positioning aidsare at least one of formed as single flat and as multiple flat.
 18. Thefunction device according to claim 17, wherein the multiple flat is atleast one of two-flat and triple-flat.
 19. The function device accordingto claim 9, wherein the individual function elements of the functiondevice comprise positioning aids, wherein the positioning aids allowfixing of the individual function elements to one another in apredefined angular position.
 20. The function device according to claim19, wherein the positioning aids are at least one of formed as singleflat and as multiple flat, and wherein the multiple flat includes atleast one of two-flat and triple-flat.